Endometriosis affects up to 10% of all fertile women, and is associated with symptoms like infertility, dysmenorrhea, deep dyspareunia and chronic pelvic pain. 10-25% of endometriosis patients need artificial reproductive techniques (ART) to become pregnant. Endometriosis is estrogen dependent, and in theory this means, that the increased levels of estrogen during fertility treatment will worsen endometriosis symptoms. Endometriosis is a benign disease, and treatment is guided by the patient's symptoms. Worsening of endometriosis symptoms during fertility treatment may result in cessation of the treatment, operation and risk of complications.